PC owners can currently get GRID 2 and a couple of pieces of DLC for free from Humble.
Simply head on over to the Humble Store, sign up for a free account (or log into an existing one), and get the game. In addition to the game, Humble is giving away the Bathurst Track Pack and Spa-Francorchamps Track Pack for free, which include the two tracks and a number of new cars.
The game will be free to download until March 17th at 10 a.m. PT, or until Humble runs out of codes.
GRID 2 originally released for Xbox 360, PlayStation 3, and PC in May 2013.